1. CELL STRUCTURE AND FUNCTION Lab 3

2. Objectives Be able to make a wet mount of any cellular material provided and focus on a cell. Be able to stain cells with either Lugol’s solution or methylene blue. Be able to determine the length and width of cells in micrometers and/or millimeters. Be able to diagram any cell observed through the microscope. Be able to locate the following structures in an onion cell: cell wall vacuole nucleus cytoplasm cell membrane.

3. THE CELL The cell concept is basic to understanding the activities and characteristics of organisms. Cells are the units of structure and function of an organism.Cells are the units of structure and function of an organism. As units, they reflect the abilities of the organism as a whole. Cells are of interest because of their variety and also because of their similarities.

4. In this exercise, we will examine the cell. We will try to determine the three-dimensional shape of theses cells and identify some of their structures. The cell is compose by three principal compartiment: 1.- Plasmatic membrane 2.- Cytoplasm (organelles) 3.- Nucleous

5. Plasma Membrane Figure 3.3

6. Cytoplasma It is the specialized living material of cells It lies between the plasma membrane and the nucleus Numerous small structure (organelles) are part of the cytoplasma, along with the fluid that serves as the interior environment of each cell

7. Organelles Ribosomes Endoplasmic reticulum Golgi apparatus Mitocondria Lysosomes Centrioles

9. Nucleus Contains nuclear envelope, nucleoli, chromatin, and distinct compartments rich in specific protein sets Gene-containing control center of the cell Contains the genetic library with blueprints for nearly all cellular proteins Dictates the kinds and amounts of proteins to be synthesized

10. Nucleoli Dark-staining spherical bodies within the nucleus Site of ribosome production

11. Nucleus Figure 3.28a

12. CELL PART STRUCTURE FUNCTION(S) Plasma Membrane Phospholipid bilayer studded with proteins Serves as the boundary of the cell. P and C (outer surface) perform various functions (Ex. markers and receptor) RibosomesTiny particles each made up of rRNA subunits Synthesize proteins; a cell’s “protein factories” Endoplasmic Reticulum (ER) Membranous network of interconnected canals and sacs, some with ribosome (rough ER) and some without (smooth ER) Rough ER receives and transports synthesized proteins Smooth ER synthesizes lipids and carbohydrates

13. CELL PART STRUCTURE FUNCTION(S) Golgi apparatus Stack of flattened, membranous sacs Chemically processes, then packages substances from ER MitochondriaMembranous capsule containing a large, folded membrane encrusted with enzyme ATP synthesis; a cell’s “powerhouse” Lysosomes“Bubble” of enzymes encased by membrane A cell’s “digestive system”

14. CELL PART STRUCTURE FUNCTION(S) NucleusDouble-membrane, spherical envelope containing DNA strands Dictates protein synthesis, thereby playing and essential role in other cell activities, namely active transport, metabolism, growth and heredity NucleolusDense region of the nucleus Plays an essential role in the formation of ribosomes

15. During this lab exercise you can: Prepare sections of onion membrane, make a temporary wet mount, and view the specimen through a microscope. Prepare sections of onion membrane, make a stained temporary wet mount, view through a microscope, and sketch a generalized cell. Collect cheek epithelial cells, make a stained temporary wet mount, view through a microscope, and make drawing of the structure of a generalized cheek cell. Make a temporary wet mount of Elodea, view it through a microscope and make drawing of the structure of a generalized cheek cell.

16. Locate the following structures: cell wall (thick, clear band which surrounds the cell) cytoplasm (granular material in the cell next to the cell wall) nucleus (football-shaped object in the cell) vacuole (large, central, nongranular space) cell membrane (thin membrane just inside the cell wall. If you place a drop of 5% salt solution on the onion tissue, the size of the cell will shrink and the cell membrane will pull away from the cell wall revealing the cell wall and the cell membrane are separate structures).